demo handle_move_event() functionality

src/game.d

@@ -30,6 +30,8 @@ public:
     }
     void handle_move_event(int type, bool stop)
     {
+        m_players[m_pindex].x += [-10, 10, 0, 0][type];
+        m_players[m_pindex].y += [0, 0, 10, -10][type];
     }
     Player[] get_players() { return m_players; }
 protected: